iOS Safari does support service workers and "add to home screen". You can't however prompt the user for "add to home scree" - the user has to do it via the Safari menu. The notification dialog is a disaster in Chrome as all sites asks for it, few sites asks to be installed on the desktop though. Safari does lack some functionality that Chrome has - maybe Safari could add that functionality if the user adds the web site/app to the home screen... like native file system, Bluetooth api, etc.